#attenuated strain
- Avirulent — Regarding microorganisms (bacteria, viruses): devoid of virulence or pathogenicity; lacking the structural capacity to trigger an infectious disease in the host organism. In a technical sense, it describes microbial strains artificially attenuated in the laboratory or natural mutants, frequently used as active agents in the production of live attenuated vaccines.
- Avirulent — Lacking virulence; a microorganism, bacterium, or virus that does not possess the capacity to cause disease or produce toxic effects within a host organism, although it may retain its antigenic properties. In immunology, avirulent strains are frequently used to develop live attenuated vaccines, as they stimulate a protective immune response without triggering the associated pathology.